Revised for Gulp v4: Automatically reload your node.js app on file change with Gulp (https://github.com/wearefractal/gulp).

Simple Node Gulpfile.js

// jshint esversion: 6, asi: true, laxcomma: true

const gulp = require('gulp')
    , spawn = require('child_process').spawn
    , killer = node => node ? node.kill() : null
    , config = {
        init: ['index.js'],
        watch: ['*.js']
    }
;

let node

const server = () => {
    
  killer(node)

  node = spawn('node', config.init, {stdio: 'inherit'})
  
  node.on('close', code => {
    if (code === 8) {
      gulp.log('Error detected, waiting for changes...')
    }
  })
}

const task = cb => {

    gulp.watch(config.watch, cb => server(cb()))
    server()
    cb()
}
  
exports.default = task